1. Field of the Invention
This invention relates to a method for repairing a tube in a header or drum by replacing an old tube with a new tube without entirely removing the old tube.
2. Description of the Prior Art
In many applications in boilers and steam equipment, an array of tubes penetrates some kind of sealing plate, such as a tube sheet in a steam generator, or a drum or header in other applications. Particularly in drums and headers, these tubes may be subject to chemical and thermal corrosion and other degradation and may need to be replaced. In the prior art, such tubes were generally removed from the header or drum (generically a header-member) and wholly replaced with a new tube, which had to be expanded into the header-member to form a seal. Old tubes are typically removed from the header-member by cutting two opposed lengthwise slits through the portion of the tube that penetrates the header-member and then squeezing the tube pieces together so that the tube can be extracted from the header-member. Typically the slits are cut with a cutting torch, which generally results in damage to the hole in the header-member. Both these problems make tube replacement awkward and extremely time consuming and expensive.
Accordingly, there is a clear need for an improved method of repair of defective tubes in header-members that is less costly and significantly reduces the possibility of damaging the header-member.